Planar Magic-Ts are used in microwave integrated circuits to split or combine in-phase and out-of-phase signals. Applications include balanced-mixers, discriminators, interferometers, and beam-forming networks. Desirable properties of a magic-T include wide bandwidth phase and amplitude balance, low insertion loss, high isolation, compact size, and fabrication simplicity.
Several techniques have been developed to provide broadband response to a Magic-T. Co-planar waveguide (CPW) or microstrip (MS) to slotline (SL) mode conversion techniques are widely incorporated in a Magic-T to produce a broadband out-of-phase power combiner or divider such that the slotline transmission becomes the main part of these Magic-Ts. Since a slotline has less field confinement than a microstrip or a CPW, slotline radiation can cause high insertion loss in these Magic-Ts. In addition, the Magic-T constructed from CPW transmission lines requires the bonding process for air bridges which increases fabrication complexity. Although aperture coupled Magic-Ts have a small slot area, however, aperture coupled Magic-Ts require three metal layers causing high insertion loss and radiation.
For at least the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for Magic-T is compact and has less slotline radiation loss. There is also a need for improved Magic-T with reduced slotline radiation.